Warm Weather May Hinder Manatee Count

February 8, 2002|By Ludmilla Lelis, Sentinel Staff Writer

The warm winter weather may disrupt the state's annual wintertime count of manatees for the first time in seven years.

As manatees find refuge during the coldest of the cold snaps, scientists are able to count them at springs and waterways near power plants, areas where the endangered sea cows find warm water. So far this winter, however, there hasn't been a cold front that makes the counting worthwhile.

"We're still holding out some hope that we could do the survey by March," said Elsa Haubold, research administrator at the Florida Marine Research Institute.

Though there have been freezes as late as March, freezing weather becomes rare as the year progresses, said Tony Cristaldi, senior forecaster for the National Weather Service in Melbourne.

"It's certainly possible, though the likelihood starts to trail off in February," Cristaldi said. "At the moment, there is nothing on the horizon to suggest we're in for a freeze in the next week or two."

The warm weather, measuring about 2.5 degrees above normal for Central Florida and as much as 10 degrees above normal for South Florida, is not only hampering the manatee count, but it may be bad for manatees, as well.

Instead of staying in protected refuges, the manatees are dispersed throughout the state, making them more vulnerable to boat-collision deaths.

Last month, 16 manatees died from boat collisions, the highest number for a single month, according to the Florida Fish and Wildlife Conservation Commission. State officials think the manatees collided with boaters who are also enjoying the warm spells.

Still, it's too warm to conduct a count. There may not be many consequences, if there's no count.

The annual survey results will not affect any state or federal program, nor do scientists depend on them for other manatee population studies. Those who argue about manatee protection say the counts do little, but fuel more debate.

Manatee surveys started in 1991, when a group of scientists flew over the known manatee winter refuges during a January cold spell and counted 1,268 sea cows. The counts have continued through the years, and last year's count became a celebrated event, when the survey team counted a record-setting 3,276 manatees.

The Legislature has even mandated the counts, which cost more than $10,000 to conduct, hoping to have an "impartial, scientific" census of the state's manatee population. However, the count is so weather-dependent that they are not an entirely reliable measure of the manatee population, scientists and activists say.

An ideal manatee count requires air temperatures remain in the low 40s and water temperature below 64 degrees, both of which are tracked near the institute's St. Petersburg office, Haubold said.

That type of chill needs to last several days, which forces the cold-sensitive manatees to take refuges at springs and near power plants, areas with warmer water. Also, the counts depend on sunny weather, which makes it easier to see the manatees in the water, and slow winds, which create fewer ripples, Haubold said.

The highest counts, occurring in 1996 and 2001, coincided with perfect counting conditions. In other years, with less than ideal conditions, the counts were lower.

"I don't feel the surveys are a useful tool for understanding manatee population because of the environment factors," said Lynn Lefebvre, project leader for the manatee research team at the U.S. Geological Survey.

Instead, researchers look toward other long-term studies, tracking specific groups of manatees over 10-year spans, as more accurate ways of understanding the population, she said. Those long-term studies, which are the highlight of a manatee scientific conference planned for April, track reproduction rates and survival rates and the scientists don't use the annual surveys as part of its statistics, she said.

Even the U.S. Fish and Wildlife Service, the primary federal agency overseeing manatee protection, acknowledged in its 2001 Florida Manatee Recovery Plan that the annual surveys are limited in their usefulness.